[mdns] add API support for custom hostname
This commit adds support of regsitering a service with a custom
hostname. This is required to enable Advertising Proxy feature for Thread
devices.
For example:
```
NsdServiceInfo info = new NsdServiceInfo();
info.setServiceName("My Service");
info.setServiceType("_test._tcp");
info.setHostname("MyHost");
info.setHostAddresses(List.of(address1, address2));
nsdManager.registerService(info, PROTOCOL_DNS_SD, listener);
```
This CL also adds two new error codes for service/host registration
conflict: `FAILURE_SERVICE_NAME_CONFLICT` and
`FAILURE_HOST_NAME_CONFLICT`.
Bug: 284904661
Test: atest CtsNetTestCases FrameworksNetTests
Change-Id: I2fb974c38d851ba99144a18c7047084bbd61b938
5 files changed